3D-printed (lattice structured) metal-plastic matrix compound material

ABSTRACT

The present disclosure relates to a method of producing a compound material comprising at least one metal and at least one polymer, a compound material comprising at least one metal and at least one polymer, comprising a 3D-lattice of the at least one metal and a polymer introduced into the 3D-lattice, a component for a vehicle comprising the compound material and a vehicle comprising the component.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims priority to and the benefit of GermanPatent Application No. 102019201896.3, filed Feb. 13, 2019, the entirecontents of which is incorporated herein by reference.

FIELD

The present disclosure relates to a method of producing a compoundmaterial comprising at least one metal and at least one polymer, acompound material comprising at least one metal and at least onepolymer, comprising a 3D-lattice of the at least one metal and a polymerintroduced into the 3D-lattice, and a component for a vehicle comprisingthe compound material and a vehicle comprising the component.

BACKGROUND

The statements in this section merely provide background informationrelated to the present disclosure and may not constitute prior art.

Reducing vehicle weight may reduce fuel consumption and thereforedecrease the impact on the environment. In order to reduce weight inautomotive parts, composite materials of metal and plastic have beendeveloped.

For example, DE 10358295 B4 discloses a lightweight composite materialprovided with a lightweight carrier material, and a cover layer providedon at least one flat surface of the carrier material.

In US 20160237828 A1 a method of building an article by a layer-by-layeradditive manufacturing process is described.

The disclosure disclosed in WO 2017/102943 A1 relates to a process ofmanufacturing a plastic-metal hybrid part by plastic overmolding on ametal surface via nano-molding technology (NMT).

All these methods leave room for improvement, though, particularlyregarding structuring of composite materials.

SUMMARY

The recent development of 3D-printing technology has had an impact inthe automotive sector and led to a growth in application thereof,particularly as a key point in lightweight design. Due to the designfreedom in 3D-printing it is possible to design hollow structures,instead of full solid parts to achieve a high lightweight index.

One structural design of a 3D-lattice of at least one metal as can beprovided with 3D printing can be seen in FIG. 2.

However, in such parts, there can be a lack of sealability againstfluids like water, local forces could break the part locally, and due tothe lattice structure brittleness could be higher.

The inventor has found that a compound material of 3D-printing metal anda polymer, particularly as a matrix, can be made from which componentscan be produced that have a good seal against fluids with increasedlocal stiffness and increased ductility, particularly by injecting thepolymer, e.g. a plastic. For example, a weight reduction of 30% or morecompared to a solid metal of the same volume and a stiffness increase of10% or more compared to the 3D-lattice of the metal without the polymercan be obtained by obtaining the metal lattice with the polymer.

In a first aspect a method of producing a compound material comprisingat least one metal and at least one polymer is disclosed, comprising3D-printing a 3D-lattice of the at least one metal; and introducing theat least one polymer into the 3D-lattice.

A second aspect of the present disclosure relates to a compound materialcomprising at least one metal and at least one polymer, comprising a3D-lattice of the at least one metal and a polymer introduced into the3D-lattice, wherein the amount of metal is in a range between andincluding about 10 vol. % and about 80 vol. %, or between and includingabout 15 vol. % and about 70 vol. %, or between and including about 20vol. % and about 65 vol. %, or between and including about 30 vol. % andabout 60 vol. %, and wherein the 3D-lattice of the at least one metalcomprises holes and/or pores whose difference in diameter is at most35%, or at most 30%, or at most 25%, or at most 20%.

A third aspect of the present disclosure is directed to a component fora vehicle, comprising the compound material of the present disclosure.

Furthermore, a fourth aspect of the present disclosure discloses avehicle, comprising the component for a vehicle of the presentdisclosure.

Further aspects of the disclosure are disclosed in the dependent claimsand can be taken from the following description and examples, withoutbeing limited thereto.

Further areas of applicability will become apparent from the descriptionprovided herein. It should be understood that the description andspecific examples are intended for purposes of illustration only and arenot intended to limit the scope of the present disclosure.

DRAWINGS

In order that the disclosure may be well understood, there will now bedescribed various forms thereof, given by way of example, referencebeing made to the accompanying drawings, in which:

FIG. 1 shows schematically a method of the present disclosure;

FIG. 2 is a schematic view of a metal lattice;

FIG. 3 depicts a metal lattice impregnated with a polymer, as can beproduced by the present method;

FIG. 4 illustrates diameters d for round holes in a metal lattice part;and

FIG. 5 illustrates virtual circles in corners of holes of any shape in ametal lattice part.

The drawings described herein are for illustration purposes only and arenot intended to limit the scope of the present disclosure in any way.

DETAILED DESCRIPTION

The following description is merely exemplary in nature and is notintended to limit the present disclosure, application, or uses. Itshould be understood that throughout the drawings, correspondingreference numerals indicate like or corresponding parts and features.

Unless defined otherwise, technical and scientific terms used hereinhave the same meaning as commonly understood by one of ordinary skill inthe art to which this disclosure belongs.

A lattice is an open framework made up of criss-crossed patterns and/orstrips and/or wires that can be regular or irregular. According tocertain aspects the lattice is regular. In the lattice thicknesses ofstrips and/or wires forming the lattice is not particularly restricted,and/or the size of openings is not particularly restricted. The openingscan have a regular or irregular shape. According to certain aspects,corners in the lattice are substantially rounded off, i.e. there isessentially no angle in the corners of the network between differentconnecting strips and/or wires bigger than 30°, or bigger than 20°, orbigger than 15°. This does not exclude, though, that different anglesmay be present in the lattice between two strips and/or wires. Theangles, openings, strips, wires, etc. can be properly designed by asuitable program that controls the 3D-printer. While the above latticeis described with regard to two dimensions, the 3D-lattice produced inthe present method, respectively comprised in the present compoundmaterial, can also show the respective properties in three dimensions,e.g. have substantially rounded corners in three dimensions, i.e. thereis essentially no angle in the corners of the network between differentconnecting strips and/or wires bigger than 30°, or bigger than 20°, orbigger than 15° in three dimensions in the 3D-lattice as well. Again,though, different angles can be present in the lattice between twostrips and/or wires. Further, the 3D-lattice may also be substantiallyan open framework or an open network, i.e. does not contain any closedoff areas that cannot be penetrated by the at least one polymer. Thetype of network is not particularly restricted, and it can be regular orirregular. When the network is regular, it may have repeating structureswithin the lattice, respectively the 3D-lattice.

All values given in the present disclosure are to be understood to becomplemented by the word “about”, unless it is clear to the contraryfrom the context.

As used herein, wt. % is to be understood as weight percent. In thepresent disclosure, all amounts are given in wt. %, unless clearlystated otherwise or obvious from context. In the present disclosure,furthermore all amounts given in wt. % in a particular variation add upto 100 wt. %. Likewise, all amounts given in vol. % in a particularvariation add up to 100 vol. %. The weight percent, respectively volumepercent, are thereby calculated by dividing the mass, respectivelyvolume, of each component by the total mass, respectively volume, in therespective aspect, unless indicated otherwise or clear from context.

In a first aspect the present disclosure relates to a method ofproducing a compound material comprising at least one metal and at leastone polymer, comprising

-   -   3D-printing a 3D-lattice of the at least one metal; and    -   introducing the at least one polymer into the 3D-lattice.

In the present method the 3D-printing is not particularly restricted andcan be carried out in any suitable way used for printing metal in a3D-printing process. For example, it can be done by laser melting, e.g.selective laser melting. Also, the 3D-lattice produced by the3D-printing is not particularly restricted as long as a 3D-lattice isproduced. The printing can be done any suitable way with any basicmaterial comprising at least one metal, e.g. comprising or consisting ofone or more metals, for example comprising or consisting of one metal.

Further, the at least one metal is not particularly restricted as longas it can be printed by 3D-printing. According to certain aspects, theat least one metal comprises aluminium, steel and/or titanium. Accordingto certain aspects, the at least one metal is aluminium, titanium,and/or steel, e.g. aluminium.

In addition, also the introducing of the at least one polymer into the3D-lattice is not particularly restricted. While it is not excluded thatthe polymer is only forming inside the 3D-lattice, e.g. by apolymerization reaction which is not particularly restricted, accordingto certain aspects the polymer is already formed outside the 3D-lattice,e.g. provided as a bulk polymer, molten and introduced into the3D-lattice.

The introducing into the 3D-lattice can be carried out in a way that the3D-lattice is only partially filled by the at least one polymer, e.g.with at least 20 vol. %, e.g. at least 50 vol. %, e.g. at least 70 vol.%, or at least 80 vol. %, or at least 90 vol. % of the void spaces inthe 3D-lattice. According to some aspects, the 3D-lattice of the atleast one metal is essentially filled by introducing the at least onepolymer, i.e. filled with at least 95 vol. %, or at least 98 vol. %, orat least 99 vol. %, e.g. at least 99.5, 99.8 or 99.9 vol. % of the void(empty) space in the 3-D lattice. It is not excluded that also thesurface of the 3D-lattice is covered by the at least one polymer andoptionally smoothened. Of course also more than one polymer can beintroduced in one or more different introducing steps. According tocertain aspects one polymer is introduced in the 3D-lattice. Afterintroducing the at least one polymer, it is not excluded that thecompound material is further covered, e.g. with a cover layer of adifferent material, e.g. one or more polymer.

According to certain aspects, the introducing of the at least onepolymer is carried out by injection, in some aspects injection molding.The injection is not particularly restricted, and it can be e.g. done bydipping the 3D-lattice into the molten at least one polymer or pouringthe at least one polymer onto the lattice. For the introduction of theat least one polymer into the 3D-lattice, the 3D-lattice can be in ashape fitting the 3D-lattice, for example, with one or more openingsand/or exits for introducing the at least one polymer. In such aspectsat least one polymer may be formed beforehand, so that no big changes insize occur, as is e.g. possible in a polymerization reaction. Also theinjection molding is not particularly restricted and the 3D-lattice canbe introduced in a suitable form. This way a further processing afterthe polymer has hardened can be reduced.

According to certain aspects, the at least one polymer is introducedinto the 3D-lattice at a pressure of at least 10 MPa, or at least 15MPa, or at least 20 MPa. The introduction at a higher pressure mayenable better filling of the 3D-lattice, particularly when the openingsand/or holes in the 3D-lattice are smaller. The pressure for introducingthe at least one polymer therein can e.g. depend on the openings in thelattice, the at least one polymer applied, etc.

After introducing the at least one polymer it can be hardened, e.g. bycooling, and optionally post-processed, e.g. by milling, as describedbelow.

The at least one polymer that is introduced is not particularlyrestricted as long as it can be introduced. According to certainaspects, the at least one polymer comprises at least one thermoplasticpolymer which is not particularly restricted. Thermoplasts can be moltenand can sufficiently retain a certain volume. Thermoplasts comprise e.g.acrylic, acrylonitrile butadiene styrene (ABS), polyamide, polylacticacid (PLA), polybenzimidazole, polycarbonate, polyether sulfone,polyoxymethylene, polyetherether ketone, polyetherimide, polyethylene,polyphenylene oxide, polyphenylene sulfide, polypropylene, andpolystyrene. According to some aspects, the at least one polymer isselected from the group consisting of acrylonitrile butadiene styrene(ABS), polyethylene (PE), polypropylene (PP), polystyrene (PS),polyamide (PA), polycarbonate (PC), polyoxymethylene (POM), and(meth)acrylate. With these polymers sufficient hardness, ductility andlightweight can be achieved. According to certain aspects the at leastone polymer comprises or consists of at least one plastic. A plastic isa material consisting of any of a wide range of synthetic orsemi-synthetic organic compounds that are malleable and so can be moldedinto solid objects.

According to certain aspects, the method further comprises shaping thecompound material into a desired shape, in some aspects including atleast one milling step. The shaping is not particularly restricted andcan comprise usual shaping process, e.g. as in usual processes forproducing vehicle parts, for example in the automotive sector. Anexemplary shaping process can e.g. comprise a milling step which is notparticularly restricted. The compound material can be easily shaped asit may be essentially homogeneous or homogeneous due to a regularstructure in the 3D-lattice, thus enabling a shaping with reducedoccurrence of breaking, cracking, chipping of during shaping, or evenavoiding it at all.

An exemplary method of the present disclosure is shown schematically inFIG. 1. In a step 1 3D-printing of a 3D-lattice of the at least onemetal is carried out. Afterwards, in step 2 the at least one polymer isintroduced into the 3D-lattice, e.g. by melting, injecting andhardening. In the optional step 3 the compound material is then shaped,e.g. by milling. As a result, compound material as schematically shownin FIG. 3 can be obtained, wherein the at least one polymer 5 iscontained in the 3D-lattice of the at least one metal 4.

According to certain aspects, the amount of metal is in a range betweenand including about 10 vol. % and about 80 vol. %, or between andincluding about 15 vol. % and about 70 vol. %, or between and includingabout 20 vol. % and about 65 vol. %, or between and including about 30vol. % and about 60 vol. %. If the amount of the at least one metal istoo low, no sufficient hardness and/or stiffness can be obtained. If theamount of the at least one metal is too high, the weight reduction istoo little and ductility may be reduced.

According to certain aspects, the 3D-lattice of the at least one metalcomprises holes and/or pores whose difference in diameter is at most35%, or at most 30%, or at most 25%, or at most 20%. If the differenceis too big, a homogeneous and/or essentially complete or completefilling of the 3D-lattice may be difficult to achieve, leading possiblyto remaining pores.

According to certain aspects, a minimum radius in holes and corners ofthe 3D-lattice of the at least one metal is 0.20 mm or more, or 0.25 mmor more. If the radius is too small, a complete filling of cornersand/or holes may be difficult to achieve. For different polymers,different minimum radius may apply, optionally together with differentpressures for introducing the at least one polymer. However, if theradius is too big, of course the minimum amount of the at least onemetal may not be contained anymore. The measurement of the radius willbe described below.

Table 1 shows different recommended minimum radii and pressures fordifferent polymer materials and 99% filling of the void volume in the3D-lattice.

TABLE 1 mimimum recommended radius and pressure for different polymermaterials Minimum Recommended pressure Plastic recommended needed tofill compound Material radius material 99% full* ABS  0.6 mm 800 BarPolypropylene (PP) 0.35 mm 300 Bar Polystyrene (PS) 0.45 mm 500 BarPolyamide (PA), e.g. PA6 0.25 mm 200 Bar Polycarbonate (PC)  0.5 mm 600Bar Acetal (POM) 0.40 mm 400 Bar Acrylic 0.35 mm 300 Bar *based on thevoid volume in the compound material

When designing the 3D-lattice, the at least one polymer to be appliedthus should be considered according to certain aspects. For example, theviscosity of the molten at least one polymer can be considered bydesigning the shape of hollow spaces, e.g. angles, size, etc. Of coursea suitable viscosity also can be e.g. achieved by choosing a suitablepolymer and/or introduction temperature, depending on the at least onepolymer. In some aspects, all holes inside the 3D-lattice may beconnected to each other, i.e. essentially no (less than 5 vol. %, basedon the void/empty volume in the 3D-lattice) or no dead ends should becontained so that the at least one polymer can enter all hollow areas.

For determining the minimum radius in holes and corners, as given above,two different shapes can be considered. For round shapes, as shownschematically in FIG. 4, the radius is ½ of the inner diameter d of thehole, e.g. 0.25 mm for polyamide. If the hole is not circular, theradius can be determined by fitting a circle inside the curvature anddetermine ½ of its diameter d, as exemplarily shows in FIG. 5. WhileFIG. 5 shows two strips and/or wires of the lattice at about a 90°angle, of course fitting of a circle in the curve can also be suitablycarried out for other angles, thus also other shapes. Due to plasticviscosity of the at least one polymer the angles of inside holes and/orcurvatures may be thus considered when designing the lattice structure.For filling with the at least one polymer, all openings and holes in the3D lattice may be connected to each other

As stated above, to achieve good filling of the 3D-lattice structure bythe at least one polymer, at least the minimum radius of the holestructures and the pressure during introduction of the at least onepolymer, e.g. a molding pressure, should be considered due to differentviscosity of the at least one polymer.

It is not excluded in the present method that the at least one metal istreated after 3D-printing to produce a lattice thereof and beforeintroducing the at least one polymer. For example, an electro-coating ofthe metal or a similar process can be applied. In this way the metal canbe passivated against external influences, e.g. oxidation, which can beparticularly useful as the surface of the metal is increased during3D-printing.

Alternatively it is of course also not excluded that the 3D-printing isthe only step before introducing the at least one polymer. In such acase it is also possible that 3D-printing is either carried out in airor in an inert atmosphere.

A second aspect of the present disclosure relates to a compound materialcomprising at least one metal and at least one polymer, comprising a3D-lattice of the at least one metal and a polymer introduced into the3D-lattice, wherein the amount of metal is in a range between andincluding about 10 vol. % and about 80 vol. %, or between and includingabout 15 vol. % and about 70 vol. %, or between and including about 20vol. % and about 65 vol. %, or between and including about 30 vol. % andabout 60 vol. %, and wherein the 3D-lattice of the at least one metalcomprises holes and/or pores whose difference in diameter is at most35%, or at most 30%, or at most 25%, or at most 20%.

The present compound material can particularly be produced by the methodof the present disclosure. Thus, aspects described with respect to thepresent method also apply to the compound material of the presentdisclosure.

In some aspects, all holes inside the 3D-lattice may be connected toeach other, i.e. essentially no (less than 5 vol. %, based on thevoid/empty volume in the 3D-lattice) or no dead ends should be containedso that the at least one polymer can enter all hollow areas.

According to certain aspects, a minimum radius in holes and corners ofthe 3D-lattice of the at least one metal is 0.20 mm or more, or 0.25 mmor more.

As stated above, for determining the minimum radius in holes andcorners, as given above, two different shapes can be considered. Forround shapes, as shown schematically in FIG. 4, the radius is ½ of theinner diameter d of the hole, e.g. 0.25 mm for polyamide. If the hole isnot circular, the radius can be determined by fitting a circle insidethe curvature and determine ½ of its diameter d, as exemplarily shows inFIG. 5. While FIG. 5 shows two strips and/or wires of the lattice atabout a 90° angle, of course fitting of a circle in the curve can alsobe suitably carried out for other angles, thus also other shapes. Due toplastic viscosity of the at least one polymer the angles of inside holesand/or curvatures may be thus considered when designing the latticestructure. For improving filling with the at least one polymer, allopenings and holes in the 3D-lattice may be connected to each other.

While the at least one metal and/or the at least one polymer are notrestricted in the present compound material, according to certainaspects, the at least one metal comprises aluminium, steel and/ortitanium, and/or the at least one polymer comprises at least onethermoplastic polymer, in some variations at least one polymer selectedfrom the group consisting of acrylonitrile butadiene styrene (ABS),polyethylene (PE), polypropylene (PP), polystyrene (PS), polyamide (PA),polycarbonate (PC), polyoxymethylene (POM), and (meth)acrylate.According to certain aspects the at least one polymer comprises or is aplastic.

According to certain aspects, the compound material is shaped, e.g. asgiven above, e.g. in the shape of a part of a vehicle, e.g. anautomobile.

A third aspect of the present disclosure relates to a component for avehicle, comprising the compound material of the present disclosure. Thecomponent of the vehicle is not particularly restricted and can be e.g.a part of a car, e.g. of a chassis, a vehicle body, e.g. car body, adoor of a vehicle, e.g. car, a closure of a vehicle, e.g. car, etc.

Furthermore, a fourth aspect of the present disclosure discloses avehicle, comprising the component for a vehicle of the presentdisclosure. The vehicle is not particularly restricted and can be e.g.an automobile, a train, a ship, etc., e.g. a passenger car, a pickup, avan, a bus, a truck, etc. According to certain aspects the vehicle is anautomobile.

The above aspects can be combined, if appropriate. Further possibleimplementations of the disclosure comprise also combinations of featuresnot explicitly mentioned in the foregoing or in the following withregard to the examples of the disclosure. Particularly, a person skilledin the art will also add individual aspects as improvements or additionsto the respective basic form of the disclosure.

EXAMPLES

The present disclosure will now be described in detail with reference toexamples thereof. However, these examples are illustrative and do notlimit the scope of the disclosure.

Example 1

A 3D-lattice with a minimum radius of 0.25 mm in holes and roundedcorners is printed by 3D-printing of a metal like aluminium, steeland/or titanium, e.g. using a selective laser melting method. In theresulting 3D-lattice PA6 in a molten state is introduced at a pressureof about 200 bar (about 20 MPa) total pressure in order to fill the3D-lattice at least 99% full (depending on the void volume) with thePA6. For determining the fill degree, e.g. slice of the filled3D-lattice can be made and observed and analyzed microscopically.

In order to avoid damage on the lattice structure, very slowlyincreasing the pressure may be desirable, e.g. depending on the sizedesign and thickness of the lattice and lattice parts in a time of 45seconds to 2 hours, for example in a time from 1 minute to 1 hour. Asnoted above, for different polymer different geometries of the3D-lattice structure and/or different pressures may be applied.

For introducing the PA6, the 3D-lattice can be e.g. put into the moltenPA6 under pressure, or the 3D-lattice can be introduced into a shape andinjection-molded with the molten PA6.

In some variations, the outside contour of the obtained part can beshaped, e.g. milled, to obtain a desired shape. After that the part canbe post-treated, e.g. coated, etc., and the final compound materialcomprising a 3D-lattice of at least one metal filled with at least onepolymer, here PA6, is obtained.

With the present disclosure, a compound material can be obtained thathas advantageous properties, like a good sealing against fluids likewater, a good spreading of a local impact force into the compoundmaterial, a decrease in local cracks, an increased local stiffness (e.g.˜10% compared to the lattice without the polymer), and an increasedductility due to introduction of the at least one polymer.

The invention claimed is:
 1. A compound material comprising at least onemetal and at least one polymer, comprising a 3D-lattice of the at leastone metal and a polymer introduced into the 3D-lattice, wherein theamount of metal is in a range between and including about 10 vol. % andabout 80 vol. %, with respect to the total volume of the compoundmaterial and wherein the 3D-lattice of at least one metal comprises aplurality of holes, a diameter of a largest hole of the plurality ofholes being at most 35% larger than a diameter of a smallest hole of theplurality of holes, wherein the 3D-lattice comprises at least onerounded corner, a minimum radius in holes and corners of the 3D-latticeof the at least one metal is 0.20 mm or more, wherein the polymer fillsat least 95 vol. % of remaining space excluding the 3D-lattice.
 2. Thecompound material of claim 1, wherein a radius of each hole of theplurality of holes is at least 0.20 mm.
 3. The compound material ofclaim 1, wherein the at least one metal comprises aluminium, steel ortitanium.
 4. The compound material of claim 1, wherein the at least onepolymer comprises at least one thermoplastic polymer.
 5. The compoundmaterial of claim 4, wherein the at least one thermoplastic polymer isselected from the group consisting of acrylonitrile butadiene styrene,polyethylene, polypropylene, polystyrene, polyamide, polycarbonate,polyoxymethylene, and (meth) acrylate.
 6. The compound material of anyof claim 1, wherein the compound material is shaped.
 7. A component fora vehicle, comprising the compound material of claim
 1. 8. A vehicle,comprising the component for a vehicle of claim 7.